In general, a work system for substrates includes plural working machines arranged in a line. A circuit substrate is conveyed from a working machine disposed upstream out of the plural working machines to a working machine disposed downstream. The plural working machines include a working machine that performs coating work such as paste soldering on a circuit substrate, a working machine that performs mounting work of electronic components on a circuit substrate, and an inspection machine that inspects the work results of a variety of work. In the system, when the inspection result of a circuit substrate inspected by the inspection machine is good, that is, when the circuit substrate inspected by the inspection machine is a normal circuit substrate (hereinafter, also referred to as “OK substrate”), the OK substrate is conveyed downstream through a predetermined path. On the other hand, when the inspection result of the circuit substrate inspected by the inspection machine is not good, that is, when the circuit substrate inspected by the inspection machine is an abnormal circuit substrate (hereinafter, also referred to as “NG substrate”), the NG substrate moves to a retracted position retracting from the predetermined path. An example of the system is described in the following patent literature.
PTL 1: JP-A-2007-123503